Azathiazolone cyanine dyes and their preparation



Patented Dec. 11, 1951 AZATHIAZOLONE CYANINE DYES AND THEIR PREPARATION Henry G. Derbyshire, Johnson City, N. Y., as- Y signor to General Aniline & Film Corporation, New York, N. Y., a corporation of Delaware N Drawing.

Application December 16, 1949, Serial No. 133,473

12 Claims. (Cl. 260305) This invention relates to azathiazolone cyanine dyes suitable as intermediates for the manufacture of triand tetranuclear cyanine dyestuffs and to a method of preparin the same.

Accordingly, the principal object of the present invention is to provide azathiazolone dyes which are not only valuable as sensitizers per se but also valuable as intermediates in the preparation of triand tetranuclear dyes.

Another object is to provide a process of preparing the said azathiazolone cyanine dyes.

Other objects and advantages will appear hereinafter.

The azathiazolone cyanine dyes of the present invention are represented by the following general formula:

wherein n represents 1 or 2, R represents an alkyl, allyl, aryl, or aralkyl group or substituted groups of this type, e. g., methyl, ethyl, propyl, butyl, isobutyl, n-amyl, isoamyl, hydroxyethyl, 'y-hydroxypropyl, fl-methoxyethyl, fi-ethoxyethyl, benzyl, p-phenylethyl, menaphthyl, fl-carboxyethyl, carboxymethyl, a-carboxyethyl, 'y-carbox'ypropyl, fi-acetoxyethyl, 'y-acetoxypropyl, carbomethoxymethyl, p-carbomethoxymethyl, B-carboethoxymethyl, phenyl, a-naphthyl, p-naphthyl, o-tolyl, p-tolyl, naphthylmethyl, and the like, R1 represents alkyl, allyl, aryl, or aralkyl group as in R, X represents an acid radical, e. g., chloride, bromide, iodide, etc., and Z represents the residue of a heterocyclic nitrogenous nucleus of the type common in cyanine dyes, e. g., oxazole, thiazole, selenazole, and their polycyclic homologues, such as those of the benzene, naphthalene, acenaphthene, and anthracene series, pyridine, and its polycyclic homologues, such as quinoline and aor fl-naphthaquinolines, indolenines, benzimidazoles, diazines, such as pyrimidines and quinazolines, thiazolines and selenazolines. The polycyclic compounds of this series may also be substituted in the carbocyclic rings with one or more groups, such as alkyl, i. e., methyl, ethyl, etcl, aryl, i. e., phenyl, or amino, hydroxy, alkoxy, i. e., methoxy, ethoxy, etc., and methylenedioxy groups, or by halogen, i. e., chlorine, bromine, or iodine atoms.

I have found that azathiazolone cyanine dyes characterized by the foregoing general formula are readily obtained in good yields by condensing any 2-amino substituted heterocyclic quaternary ammonium salt of the type commonly used in cyanine dye synthesis with an aryl isothiocyanate in the presence of an acid binding agent. The

resulting heterocyclic substituted thiourea is then condensed with an a-halogen acetic acid to yield an azathiazolone cyanine dyestuif. The condensation reaction between the Z-amino substituted heterocyclic quaternary ammonium salt and aryl isothiocyanate is conveniently eiiected in the presence of a basic tertiary organic amine as the condensing agent, such as triethylamine, tri-npropylamine, and the like. Pyridine or its homologues may be used as a solvent-diluent in the presence of a tertiary organic amine.

The resulting substituted thiourea is then fused with an a-halogen acetic acid. The condensation reaction is effected by simply fusing the coreactants or by heating them in a suitable solvent at a temperature ranging from '75150 C. for a period of 5 minutes to 3 hours. a The preparation of the substituted thioureas is carried out by condensing a heterocyclic quarternary ammonium salt of the type commonly employed in cyanine dye synthesis and containing a reactive amino group in aor y-position to the ring nitrogen atom thereof with an alkyl, aryl, or aralkyl isothiocyanate in the presence of a base, such as triethylamine in pyridine solution. The reaction is believed to take place as follows:

wherein n, 12., X and Z have the same Values as above, and R1 represents an alkyl, aryl or aralkyl group of the same value as in R.

As typical examples of 2-amino heterocyclic I nitrogenous quaternary salts, which are utilized in the condensation reaction with the alkyl, aryl, or aralkyl isothiocyanate, the following may be mentioned:

3 2-amino-p3-naphthothiazo1e ethiodide 2amino-5-ethoxy-benzothiazole ethiodide Z-aminothiazole methiodide, and the like.

The following are examples of suitable alkyl, aryl, and aralkyl isothiocyanates:

Methyl isothiocyanate Ethyl isothiocyanate Allyl isothiocyanate Phenyl isothiocyanate a-Naphthyl isothiocyanate p-Naphthyl isothiocyanate o-Tolyl isothiocyanate n-Tolyl isothiocyanate p-Tolyl isothiocyanate Benzyl isothiocyanate Phenethyl isothiocyanate, and the like.

As examples of a-halogen acetic acids, the following may be mentioned: bromacetic acid, chloracetic acid, and iodoacetic acid. 1

The condensation reaction between the substituted thiourea and a-halogen acetic acid is carried out, as pointed out above, by simply heating the coreactants at a temperature ranging from 100-120 C. for minutes to 3 hours. The reaction can also be effected by heating the coreactants in the presence of a liquid alcohol having a boiling point over 100 C. or acetic acid or anhydride for a few minutes at reflux or on a steam bath. I prefer for the sake of expediency to operate by heating the coreactants in the presence of butyl, amyl, or isobutyl alcohol and the like or in the presence of glacial acetic acid at a temperature ranging from 100-120 C. for a period of time ranging from 5 minutes to 1 hour.

The reaction involved in this case by utilizing, for example, chloracetic acid is believed to take place as follows:

wherein n, R, R1 Z, and X have the same values as above.

The following examples describe the preparation of some of the N-substituted thioureas, which are, as shown hereinafter, converted to azathiazolone cyanine dyes.

Example I N (3-ethyl-2-benz0thiaz0lylidene) -N-phenylthiourea 5.5 grams 'of 2-aminobenzothiazole ethiodide and 5 grams of phenyl isothiocyanate were dissolved in mls. of hot pyridine. The solution was heated slowly until its temperature reached 130 C. Upon cooling to C., a yellow solid crystallized which was filtered off, washed with water, dried, and purified by recrystallization 4, from methanol. The product was dried at C. A yield of 5.4 grams was obtained, melting at 158 C.

Example II N- (3-ethyl 6-ethoxy-2-benzothiaz olylidene -N- phenylthiourea 8 grams of 2-amino-6-ethoxybenzothiazole ethiodide and 5 grams of phenyl isothiocyanate were dissolved in 10 mls. of boiling pyridine. The resulting solution was stirred and slowly heated to 150 C. while permitting the pyridine to distill. Heating was discontinued, but stirring was kept up until the reaction mass cooled to 25 C. A yellowish solid separated which was washed with two 25 ml. portions of water, then triturated with 20 mls. of methanol and filtered. Afterconsecutive washings with water and methanol, the solid was dried overnight at 80 C. 6 grams of a purified product were obtained which melted at l77-180 C.

Example III HZCH=C H2 2115 N- (3-ethyl-6-ethoxy-2-benzothiazolylidene) -N-ally1- thiourea H '7 grams of 2-amino-6-ethoxybenzothiazole ethiodide and 5 grams of allyl isothiocyanate were heated together in 5 mls. of boiling pyridine. Heating was continued until the internal temperature reached 150C. The reaction mixture was 'cooled to room temperature and poured into 10 mls. of water. The yellow solid which separated was triturated with three 'fresh 10 ml. portions of methanol, filtered, washed alternately with water "and methanol, and dried. The'product melted at 1-19-1 22 C.

Example IV N (3ethyl-5-methyl-4-phenyl-2-tl1iazolylidene) N- 'phenylthiourea 6 grams of 2 -'amino-5-methy1-4-phenyl-2- thiazole ethiodideiand 4 grams of phenyl isothiocyanate were dissolved in 10 mls. of hot pyridine. The resulting solution was heated until its internal temperature reached C. The mixture was stirred slowly until cooled to 25 C. A solid separated which was diluted with 10 mls. of isopropyl alcohol, filtered, repeatedly washed with isopropyl alcohol and dried. 4.7 grams .of a lemon-white solid were obtained which melted at 183185 C.

Example V s C=N- in N 43H:

N-(3-methyl-2-benzothiazolylidene)-N'-pheny1thionrea This product was prepared from grams 01' Z-aminobenzothiazole methiodide and 5 grams of phenyl isothiocyanate by following the general procedure of Example I.

Example VI CHa-J) N- (3,4'dimethyl-2-thiazolylidene) -N -phen ylthiourea 100 grams of 2-amino-4-methylthiazole dimethylsulfate and 5.7 grams of phenyl isothio- Example VII s-cm C an \N/ One gram of the product of Example V and 1 gram of bromacetic acid were dissolved in 5 mls. of glacial acetic acid and heated for 5 minutes. The solution was cooled to room temperature, diluted with mls. of ether, and stirred vigorously until a yellow fluffy solid separated. The crystals were filtered OE and repeatedly washed with ether.

Example VIII S -CH2 5.4 grams of the compound of Example I and 5 grams of bromacetic acid 'were boiled together in mls. of glacial acetic acid for 5 minutes. The cooled solution was poured into 40 of Crystals separated ether. A yellow crystalline solid precipitated which was washed with ether.

Example IX s 5 grams of the product of Example IV and 3 grams of bromacetic acid were heated together for 20 minutes in boiling n-butanol. The mixture was cooled in ice and stirred until muddyyellow crystals separated. After 10 mls. of isopropanol had been added, the crystals were filtered off, and washed with ether.

This product, obtained in the form of a fine yellow solid, was prepared from 2 grams of the compound of Example III and 2.2 grams of bromacetic acid by following the procedure of Example VI.

This product was obtained by a process analogous to the one described in Example VII but using 3.8 grams of the compound of Example II and 4 grams of bromacetic acid as starting materials.

Example XII s s--o H1 o-N=e =0 Example VIII was repeated with the exception that 2 grams of chloracetic acid were used in place of 5 grams of bromacetic acid.

Example XIII s H OKs-- Br One gram of the compound of Example VI and 1 gram of bromacetic acid were heated together for =.2 minutes in-the presence-of 1Q mlsz. of'tglacialz" acetic acid. The paleiyellowsolution*wasxcooled'r sions-and as intermediates-for the preparation of various types of triand tetra-nuclear'cyanine dyes;-

Whilethere havebeen pointed out abovecertain preferred embodiments of the invention, the same is not limited to the foregoing examples, illustrations, or to the specific details given therein, but is capable ofvariations and modifications as to the reactants, proportions, and conditions employed.

I claim:

1. Azathiazolone cyanine dyes characterized by the following general formula:

N R XV wherein R represents a member selected from the class consisting of alkyl, hydroxyalkyl, alkoxyalkyl, aryl, and aralkyl groups, R1 represents a member selected-from the class consisting of alkyl, allyl, aryl, and aralkyl groups, X represents an acid radical, Z represents:the residue of a heterocyclic nitrogenous nucleus of the type common in cyanine dyes, and n represents an integer from 1 to 2.

2. An azathiazolone dye characterized by: the following formula:

Br& 3. An azathiazolone dye characterizedby the following formula:

4. An azathiazolone dye characterized by the following formula:

8*; 5. An azathiazolone' dye-characterized by the following formula:

6. An azathiazolone dye; characterizedwby the following formula :a. s

7. A process for the production of azathiazolone dyestuffs which comprises heating a compound of the general formula:

wherein Z represents the residue ofa heterocyclic nucleus of the type common. incyanine dyes, R represents .a member selectedfrom-the class consisting of: alkyl, hydroxyalkyl, alkoxyalkyl, aryl, and aralkyl groups, R1-representsa member selected from rthe-class consisting ofalkyl,;allyl, aryl, and aralkyl groups l andzn represents an integenfrom l to-2 with an a-halogen'acetic acid.

8. A process for the-production-of an azathiazolone dye characterized by the following which comprises heating a compound having the following-xformulai with bromacetic'acid." V

9. A processrfor the production: of an azathiazolone dye characterized by the following formula:

which comprises heating a compound having the following formula:

with bromacetic acid.

10. A process for the production of an azathiazolone dye characterized by the following which comprises heating a compound having the following formula:

with bromacetic acid.

11. A process for the production 01' an azathiazolone dye characterized by the following which comprises heating a compound having the following formula:

OHa-

\N/ NE with bromacetic acid.

12. A process for the production of an azathiazolone dye characterized by the following formula:

which comprises heating a compound having the following formula:

with bromacetic acid.

HENRY G. DERBYSHIRE.

REFERENCES CITED The following references are of recorc. in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,394,067 Kendall Feb. 5, 1946 2,464,785 Thompson Mar. 22, 1949 OTHER REFERENCES Schneider et 9.1.: Berichte, vol. 57, pages 

1. AZATHIAZOLONE CYANINE DYES CHARACTERIZED BY THE FOLLOWING GENERAL FORMULA: 